The present invention relates to an apparatus for emitting a beam to a sample used for manufacturing a semiconductor device, which has a mask forming electron beam exposure apparatus, a laser exposure apparatus, a stepper, and an electron beam direct patterning apparatus as a typical example and, more particularly, to an apparatus mounted with an optical position detector (an XYZ sensor) for determining the position of a sample, such as a semiconductor wafer and a mask, in three directions of x, y and z, without contacting the sample.
Recently the width of a circuit line required for semiconductor devices has been narrowed more and more in accordance with high degree of integration of an LSI. To manufacture such a semiconductor device, there is a method of aligning several tens of types of original pattern (reticle or mask) of a desired circuit pattern with an exposure area of a wafer with high precision and transferring it thereto, and a method of forming a pattern directly on a wafer. The wafer is finely processed through various processes.
As an apparatus for emitting a beam such as a light beam and an electron beam to a sample used for manufacturing a semiconductor device, there are a mask forming electron beam exposure apparatus, a laser exposure apparatus, a stepper, an electron beam direct patterning apparatus and the like. In this apparatus, a variation in a direction z, which is the same as the optical axis direction of a processing beam incident upon the sample face, has to be measured with high precision, because the processing beam has to be focused exactly on the sample face. Further, it is necessary to measure directions x and y, which are normal to the optical axis direction of the processing beam, using a mark in order to determine the accurate position of the sample face.
Conventionally, the above measurements are achieved independently and separated from each other. In the stepper, since a mark is located on the periphery of a semiconductor element, the position of the sample face is determined on the periphery, while that of the focus (z direction) for transferring an element pattern is done in the central part of the device. In the electron beam exposure apparatus, the position of a mark is generally determined using an electron beam (Jpn. Pat. Appln. KOKAI Publication No. 58-223326).
Since, however, resist is greatly damaged by accelerating an acceleration voltage of the recent electron beam, the high-precision measurement of the electron beam is considered to be questionable. Moreover, the electron beam has a problem of causing a drift by charge-up to make it difficult to accurately determine the position of a sample. Thus the development of a position determination technique in the optical system is expected.
Though, for example, Jpn. Pat. Appln. KOKAI Publication No. 4-315904 discloses a technique capable of determining the z-direction, it does not report an apparatus mounted with a sensing device for determining the x- and y-directions at the same time. The above method of manufacturing a semiconductor device has a problem that each of the positions cannot be determined accurately unless the x-, y- and z-directions are measured simultaneously. This is because it is known that the current optical xy measurement device is varied with a variation in position of a mark in the z-direction.
An electron beam patterning apparatus, disclosed in Jpn. Pat. Appln. KOKAI Publication No. 7-82987, includes an optical position detector capable of optically determining a position of a mark. When the position cannot be determined using an electron beam, positioning is executed by the optical position detector based on data to form a pattern.